Cyclic digold(I) complexes, containing bridging diphosphine and diacetylide ligands and with 15-to 22-membered rings, are reported. Oligomeric complexes [C 6 H 4 (OCH 2 CtCAu) 2 ] n were prepared from AuCl(SMe 2 ) and o-, m-, or p-bis(propargyloxy)benzene and then reacted with the diphosphines Ph 2 P(CH 2 ) n PPh 2 (n ) 1-6) to give the corresponding ring complexes [C 6 H 4 (OCH 2 CtCAu) 2 {µ-Ph 2 P(CH 2 ) n PPh 2 }]. Alternatively, a two-step procedure in which the soluble isocyanide complex [p-C 6 H 4 (OCH 2 CtCAuCNtBu) 2 ] was prepared, followed by displacement of the isocyanide ligands by the diphosphine, could be used. The complexes [m-C 6 H 4 (OCH 2 CtCAu) 2 (µ-Ph 2 PCH 2 PPh 2 )], [m-C 6 H 4 (OCH 2 CtCAu) 2 {µ-Ph 2 P(CH 2 ) 5 PPh 2 }], [p-C 6 H 4 (OCH 2 CtCAu) 2 {µ-Ph 2 P(CH 2 ) 3 PPh 2 }], and [p-C 6 H 4 (OCH 2 CtCAu) 2 {µ-Ph 2 P(CH 2 ) 5 -PPh 2 }] have been characterized by X-ray structure determinations. The ring complexes are emissive at room temperature and may exhibit either red or blue shifts between solution and the solid state.

Reactions of the precursor molecules [Au2(mu-BINAP)(O2CCF3)2], 1a, racemic BINAP, 1b, S-BINAP (BINAP = 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) with the easily exchanged linear bis(pyridine) ligand 1,2-trans-bis(4-pyridyl)ethylene (bipyen) gave the polymeric complex [{Au2(mu-R-BINAP)0.5(mu-S-BINAP)0.5(mu-bipyen)}n](CF3CO2)2n, 2a, but either the polymer [{Au2(mu-S-BINAP)(mu-bipyen)}n](CF3CO2)2n, 2b, or the remarkable oligomeric [Au10(mu-S-BINAP)5(mu-bipyen)4(kappa1-bipyen)2](CF3CO2)10, 3, respectively. The type of oligomer 3 is a missing link in the ring-opening polymerization of macrocyclic coordination compounds.

The reaction of [Ru2(μ-CO)(CO)4(μ-dppm)2] (1; dppm = Ph2PCH2PPh2) with CH2N2 gives the μ-methylene complex [Ru2(μ-CH2)(CO)4(μ-dppm)2] (2), and complex 2 reacts with CO to regenerate complex 1 with loss of ketene. Complex 2 reacts with HBF4 or CF3SO3H at low temperature to form the fluxional μ-methyl complex [Ru2(μ-CH3)(CO)4(μ-dppm)2]+ (3). Variable-temperature 1H, 13C, and 31P NMR studies establish that the μ-CH3 group has an unsymmetrical coordination mode with an agostic hydrogen and is fluxional. At room temperature, the reaction of 2 with formic acid gives an equimolar mixture of complex 1 and [Ru2(μ-H)(H)(μ-CO)(CO)2(μ-dppm)2] (4), which is an active catalyst for the decomposition of formic acid to hydrogen and carbon dioxide, and the reaction is shown to occur via the intermediate complexes 3 and [Ru2(μ-H){μ-C(O)Me}(HCOO)(CO)3(μ-dppm)2]+ (5). The reaction of 2 with acetic acid at room temperature gives in sequence the complexes [Ru2{μ-C(O)Me}(OAc)(CO)3(μ-dppm)2] (6) and [Ru2(μ-H){μ-C(O)Me}(OAc)(CO)3(μ-dppm)2]+ (7) before loss of methane occurs with formation of [Ru2(μ-OAc)(CO)4(μ-dppm)2]+ (8). Complex 2 reacts with methyl triflate to give ethylene and [Ru2(μ-H)(μ-CO)(CO)3(μ-dppm)2]+ (9), as the triflate salt, probably via an intermediate with an ethylruthenium group. In the presence of HBF4, complex 2 is an efficient precatalyst for the ring-opening polymerization of norbornene.

The complexes [PtMe 2 (DMEP)], 1, and [PtMe 2 (DMPP)], 2 [DMEP, DMPP ) Me 2 N(CH 2 ) n Nd CH-2-C 5 H 4 N, n ) 2, 3, respectively], contain ligands that chelate to platinum through the imine and pyridyl groups, with the tertiary amine group not coordinated. Methyl iodide reacted with complex 1 to give [PtIMe 3 (DMEP)] but reacted with 2 to give a mixture of [PtIMe 3 (DMPP)] and [PtMe 3 (DMPP)]I, indicating the greater ability of DMPP to act as a fac-tridentate ligand. Complex 2 reacted with MeO 3 SCF 3 to form [PtMe 3 (DMPP)][CF 3 SO 3 ] only. The primary reaction of 1 and 2 with HX (X ) Cl, O 2 CCF 3 , or O 3 SCF 3 ) occurred by protonation of the pendant amine, while with excess acid, a methylplatinum bond trans to imine was cleaved selectively. Two products of protonolysis, namely [PtMe(DMEP)][O 3 SCF 3 ], containing mer-tridentate DMEP, and [PtMe(O 2 CCF 3 )(DMEPH)][O 2 CCF 3 ], with a protonated bidentate DMEP ligand, have been characterized by structure determinations, and the reaction pathways have been deduced by monitoring the reactions by 1 H NMR at varying temperature. In the reaction of 2 with HCl, an intermediate hydridoplatinum(IV) complex [PtHClMe 2 (DMPPH)][Cl] was detected and determined to be stable up to -30 °C, when it decomposed to give methane and [PtClMe(DMPPH)][Cl]. NMR spectrum gave the 195 PtH couplings 3 J(PtH a ) )

A series of organoplatinum(IV) complexes has been prepared, in which one of the alkyl groups contains a functional group that is capable of taking part in hydrogen bonding. These complexes are formed by oxidative addition of reagents RCH 2 X to [PtMe 2 (bu 2 bipy)] (1; bu 2bipy ) 4,4′-di-tert-butyl-2,2′-bipyridine) and have the formulaThese complexes may form dimers through OH‚‚‚O or NH‚‚‚O hydrogen bonding or polymers through NH‚‚‚X hydrogen bonding. Further derivatives were prepared by reaction of the above complexes with AgBF 4 in the presence of nicotinic acid or 4,4′-bipyridyl (bipy9a forms a polymer by OH‚‚‚O hydrogen bonding, whereas 8 and 10a undergo hydrogen bonding with the solvent and/or the counterion. This work shows that extended structures can be designed with hydrogen bonding in organoplatinum compounds and that there is a fine balance between formation of dimers or polymers through OH‚‚‚O, NH‚‚‚O, or NH‚‚‚Cl bonding forms and formation of simpler structures arising from hydrogen bonding to solvent molecules or counterions.